A microwave oven is a cooking device that cooks food by passing microwave through the food, and uses a magnetron to generate the microwave from a supplied electric current.
Such a microwave oven is classified into a household microwave oven having a small magnetron and a commercial microwave oven having a large magnetron or a plurality of magnetrons. The microwave oven is further classified according to a heating method into a glass tray method rotating the food loaded on the glass tray and a stirrer fan method scattering radiated microwave into the cavity. The former is generally applied to the household microwave oven while the latter is applied to the commercial microwave oven. Since the commercial microwave oven is generally used at convenience stores where the microwave oven is frequently used or restaurants where a large amount of the food should be quickly heated, the commercial microwave oven needs relatively high power output compared with the household microwave oven. Due to the use of the high power, in the commercial microwave oven, a lot of heat is generated compared with the household microwave oven. Accordingly, in the commercial microwave oven, it is essentially required to exhaust the generated heat.
In the meanwhile, a great amount of heat is generated during the operation of the microwave oven. In other words, heat is first generated from the electric component chamber during the operation of the transformer and the magnetron, and heat is also generated from food heated by a microwave radiated to an inside of the cavity. If the heats are not properly exhausted to an outside, there is caused a problem that electric components of the electric component chamber do not operation normally. Also, since the inner temperature of the cavity is elevated to a very high temperature, the inner components of the cavity may be damaged or a user may be burned.
To solve the aforementioned heat radiation problem, a blower fan is installed in the electric component chamber. The air blown from the blower fan cools inner components of the electric component chamber and is then introduced into an inside of the cavity through one surface of the cavity. The air introduced into the inside of the cavity absorbs inner hot air of the cavity, is exhausted through another surface of the cavity, and then exhausted to an outside of the microwave oven.
However, when the hot air of the cavity is not exhausted properly, the hot air flows back to the inside of the electric component chamber. That is, when the hot air inside the cavity flows back to the inside of the electric component chamber through an interval between components prior to being exhausted to the outside of the microwave oven, there may be caused a phenomenon that the inner components of the electric component chamber are heated. At this time, since the air transferred to the electric component chamber contains inner heat of the cavity, the inner temperature of the electric component chamber is further elevated.
Thus, if the electric component chamber is heated, the transformer and the magnetron may operate abnormally, which can be readily presumed.
Also, when hot air of the inside of the cavity is not properly exhausted to the outside of the microwave oven, the microwave oven is spontaneously heated, so that a user may be burned and coating may be damaged.